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RIAA, Questions only please

I have closed the previous thread on RIAA and concluded that very few indeed understand the curves or the purpose. Here is my closing statement from that thread. For those who want to understand and have valid well stated questions I am happy to answer. 

Not wanting to leave the party without a clear and accurate statement I will say the following:

The answer to the question concerning noise reduction is that the simple filter that RIAA decided upon was to raise the high frequencies gradually by about 12 dB starting below 500 Hz, being up 3 dB at the 500 Hz pole. The circuit then cancells the pole with a zero at 2,200 Hz and there is then 3 dB of boosting left as one goes to 20 Khz. It is all done very gently with just two resistors and two capacitors.

By reversing this process on playback we get to enjoy 12 dB less noise above 500 Hz.

The RIAA part of things is the same for all cartridges. However we are accustomed to seeing RIAA combined with the 6 dB/octave compensation for a velocity cartridge. That takes off 12 dB, and along with two things that happen at the very ends of the response, brings the total EQ for a velocity cartridge to 40 dB. Next time you look at an RIAA curve ask yourself why there is that flat bench between 500 and 2,200 Hz.

An amplitude cartridge needs only the RIAA EQ of 12 dB. Which also speaks to the fact that the majority of the spectrum of a record is cut at constant amplitude. When you put a sewing needle in a paper cup and play the record you are getting amplitude playback not velocity.

I study these things because they interest me. Anyone can look up the parts values to make an RIAA filter or inverse RIAA. What interests me is that some manufacturers still get it wrong.

128x128ramtubes

Showing 4 responses by uberwaltz

uberwaltz's avatar
uberwaltz
13,381 posts
 
Raul,Roger ,Ralph, Al and all the other fine contributors to this thread and it's previous incarnation.

My compliments to imhififans post and link was not meant to slight any of your fine contributions and I hope that was not your takeaway from it.
I have been intrigued, enthralled and immersed in both threads since inception.
However even if you overlook the differences of opinions and the contradictions of some posts I still found myself struggling to grasp some of the technicalities of said posts at times.

What I meant in my earlier post here was that linked article was just a lot easier to comprehend and digest as a near one stop shop take on the subject.

Nothing more and hope that is understood.
uberwaltz's avatar
uberwaltz
13,381 posts
 
@imhififan 

Thank you very much
About the most complete article I have read so far that at least makes majority of sense and is somewhat easier to understand for the layman imho.

Still living and learning.
uberwaltz's avatar
uberwaltz
13,381 posts
 
Clio
That is somewhat pretentious don't you think?
Who gave you the right to decide there were only 2 or 3 "experts" whose opinions are all that is valid here?
Your opinion maybe but still as has been stated many times this is a free forum and ALL opinions are welcome as long as they remain within the posting guidelines of this forum.
Whether you like them or not or agree with them is completely irrelevant.
uberwaltz's avatar
uberwaltz
13,381 posts
 
I do hate to say so but I tend to agree with Mental and Almarg.
You truly cannot create a thread that has an obviously contentious topic and then get upset because there are a lot of opposing views and posts.
I am still not sure how much I actually learned from the last go round ( bar the fact that put 10 audiophiles in the same room and you are likely to get 10 different opinions!).
However it did contain some potential useful knowledge but deletion was not the answer imho.
More to discover